Physical Symptoms of Post-Infectious IBS
Post-infectious IBS (PI-IBS) manifests with recurrent abdominal pain occurring at least 1 day per week, accompanied by altered bowel habits (most commonly diarrhea), bloating, and changes in stool consistency that develop immediately following resolution of acute infectious gastroenteritis. 1
Core Physical Symptoms
Gastrointestinal manifestations:
- Abdominal pain or discomfort that is recurrent and typically improves with defecation 1
- Altered bowel habits with diarrhea being the predominant pattern (IBS-D subtype most common in PI-IBS) 1, 2
- Stool consistency changes characterized by loose or watery stools (Bristol Stool Scale types 6-7: mushy to entirely liquid) 3
- Bloating and abdominal distension that fluctuates throughout the day 1
- Urgency with sudden need to defecate 2
Underlying Pathophysiological Features
The physical symptoms arise from multiple mechanisms that persist after infection resolution:
- Visceral hypersensitivity causing heightened pain perception in the gut 1
- Dysmotility with altered intestinal contractions leading to diarrhea or mixed bowel patterns 1
- Persistent low-grade inflammation with ongoing immune activation despite cleared infection 1
- Dysbiosis with altered gut microbiota composition 1
- Increased intestinal permeability allowing greater exposure to luminal contents 4
- Abnormal entero-endocrine signaling affecting gut-brain communication 1
Symptom Patterns and Natural History
Temporal characteristics:
- Symptoms begin immediately after and following resolution of acute infectious gastroenteritis 1
- The acute infection typically includes ≥2 of: fever, vomiting, diarrhea, or positive stool culture 4
- Symptoms decrease over time with better prognosis than non-PI-IBS, though resolution can take years 1, 2
- Approximately 1 in 10 patients who experience acute gastroenteritis develop PI-IBS 1
Risk Factors for More Severe Symptoms
Certain factors predict worse physical symptom burden:
- Prolonged duration of initial infectious illness (strongest predictor) 2
- Toxicity of the infecting bacterial strain 2
- Female gender 1, 2
- Younger age (age >60 years may be protective) 2, 4
- Psychological factors including anxiety, depression, somatization, and negative illness beliefs 1
- Severity of acute episode with longer duration correlating with worse outcomes 1
- Smoking 2
- Antibiotic treatment during acute infection (paradoxically associated with increased PI-IBS risk) 2
Symptom Assessment
When evaluating physical symptoms, document:
- Onset, severity, and frequency using validated tools like the Gastrointestinal Symptom Rating Scale 1
- Stool frequency and consistency using the Bristol Stool Form Scale 1
- Predominant bowel pattern to classify as IBS-D (diarrhea), IBS-M (mixed), or rarely IBS-C (constipation) 1
- Perceived dietary triggers and their relationship to symptom exacerbation 1
- Impact on quality of life including social and occupational functioning 1
Common Pitfalls in Symptom Recognition
Avoid these errors:
- Overlooking the temporal relationship between infection and symptom onset—this is the defining feature of PI-IBS 1
- Assuming all IBS is psychosomatic—PI-IBS demonstrates clear organic pathophysiology with measurable inflammatory and motility changes 4
- Failing to distinguish from post-infectious malabsorption syndrome (tropical sprue), which may overlap with PI-IBS 4
- Missing alarm symptoms such as unintentional weight loss, rectal bleeding, or recent change in bowel function that warrant further investigation 5
- Ignoring psychological comorbidities that amplify physical symptom perception and perpetuate inflammation 1
Symptom-Specific Patterns by Pathogen Type
Bacterial enteritis (Campylobacter, Salmonella, Shigella) leads to prolonged PI-IBS with predominantly diarrheal symptoms 2
Viral gastroenteritis typically causes only short-term effects with better prognosis and reassurance that symptoms will likely resolve 1, 2
Protozoan and helminth infections result in persistent PI-IBS similar to bacterial causes 2